1. Field of the Invention
The present invention relates to a liquid discharge head and a liquid discharge apparatus adapted for use in a printer or a video printer as an output terminal of a copying apparatus, a facsimile apparatus, a word processor, a host computer or the like, and more particularly to a liquid discharge head and a liquid discharge apparatus having a substrate on which formed is an electrothermal converting element (heat generating element) for generating thermal energy to be utilized as energy for recording. More specifically, it relates to a liquid discharge head for use in a liquid discharge apparatus for executing recording by discharging recording liquid (ink etc.) as a flying droplet from a discharge port (orifice) and depositing such droplet onto a recording medium.
The present invention also relates to a cleaning member for removing deposit on a discharge port face of a liquid discharge head for executing recording by discharging ink, and a liquid discharge apparatus provided with such cleaning member.
2. Related Background Art
Developments and improvements are being made on the liquid discharge apparatus, particularly the ink jet recording apparatus, because such apparatus is strongly desired as a non-impact recording technology in the current business office and other office environment in which noises are undesirable, and also because such apparatus is capable of high-density recording with a high speed and can be constructed relative free of maintenance or maintenance-free.
Among such ink jet recording apparatus, that as disclosed in the Japanese Patent Application Laid-Open No. 54-59936 is strongly desired for commercialization since it is sufficiently capable of high-density recording at a high speed and it easily enables designing and manufacture of so-called full-line liquid discharge head because of its features in the configuration.
Also in the ink jet system, color recording can be easily achieved and the apparatus can be realized compact as the semiconductor technology can be utilized in manufacturing the liquid discharge head.
In such ink jet system, there is employed a liquid discharge head provided with plural ink discharge ports of a very small diameter. In the recording operation, ink is discharged from such ink discharge ports according to the input of predetermined recording signals and is deposited on a recording medium.
The recording apparatus utilizing such liquid discharge head may be associated with the following drawbacks. In an ink jet recording apparatus for discharging ink which is formed as a particle in the discharge port of a small diameter, dusts present in the apparatus, paper dusts from the recording medium or ink droplets may be deposited or solidified, as shown in FIG. 7, on the face having the discharge ports (hereinafter represented also as port face or orifice face) or in the vicinity of the discharge port (hereinafter represented also as orifice). Such deposit may render unstable the flying path of the ink particle discharged from the discharge port, or may be solidified by drying to clog the discharge port, thereby rendering the ink discharge impossible.
Such phenomena result from a fact that the orifice face of the liquid discharge head is more or less ink repellent, whereby ink droplets are present in dispersed manner on such face and are therefore dried and solidified. It has been feared that these phenomena hinder full exploitation of the excellent features of the ink jet system.
A principal object of the present invention is to provide a liquid discharge head allowing prolonged use in case high reliability is required in a full-color recording apparatus or a high-speed recording apparatus, and a liquid discharge recording apparatus utilizing such liquid discharge head.
The foregoing object can be attained, according to the present invention, by a liquid discharge head comprising a pair of substrates mutually adhered in a laminated state, plural liquid flow paths formed on the adhered face of the substrates, plural drive elements formed in a predetermined position in respective liquid flow paths, and orifices communicating with the ends of the liquid flow paths, in which the liquid is discharged from the orifice by the function of the drive element, wherein a face constituting the external surface of a member forming the orifices is coated with a material with superhydrophilicity.
In the present invention, the aforementioned drive element is a heat generating element which generates thermal energy, and there is provided a liquid discharge head in which the heat generating element causes the liquid in the liquid flow path to boil thereby generating a bubble in the liquid and the liquid discharged from the orifice by a pressure generated at the generation of the bubble.
According to the present invention, there is provided a liquid discharge head comprising a discharge port for discharging liquid, a liquid flow path communicating with the discharge port, a heat generating element formed in a predetermined position on the liquid flow path, and a supply aperture for supplying the liquid flow path with the liquid, in which the heat generating element causes the liquid in the liquid flow path to boil thereby generating a bubble and the liquid is discharged from the discharge port by a pressure generated at the generation of the bubble, wherein a face constituting the external surface of a member forming the orifices is coated with a material with superhydrophilicity.
In the present invention, the contact angle between the aforementioned material with superhydrophilicity and the liquid can be 5xc2x0 or less. Also there is provided a liquid discharge apparatus provided with the aforementioned liquid discharge head. Also there is provided a liquid discharge head including the aforementioned liquid discharge head and a cleaning member for removing the stain deposited on the face constituting the external surface of the orifice forming member without contacting such face.
In the present invention, there may be provided an ultraviolet light source for maintaining the superhydrophilicity of the aforementioned face over a prolonged period. Otherwise there may be provided an aperture for introducing, from the exterior, ultraviolet light for maintaining the superhydrophilicity of the aforementioned face over a prolonged period.
According to the present invention, there is provided a method for producing a liquid discharge head, comprising a step of forming plural drive elements on a surface of at least one of substrates, a step of forming plural liquid flow paths so as to respectively correspond to the drive elements, a step of adjoining the substrates in such a laminated state that the surface bearing the liquid flow paths constitutes the adjoined surface, a step of forming a member for forming orifices at an end of the adjoined substrates, a step of coating the face constituting the external surface of the aforementioned member with a material with super hydrophilicity, and a step of causing the orifices to communicate with the respective liquid flow paths.
According to the present invention, there is provided a method for producing a liquid discharge head comprising a step of forming an element substrate consisting of silicon on a surface of at least one of substrates, a step of forming plural heat generating elements for generating thermal energy on the element substrate, a step of forming plural liquid flow paths so as to respectively correspond to the heat generating elements, a step of adjoining the substrates in such a laminated state that the surface bearing the liquid flow paths constitutes the adjoined surface, a step of forming a member for forming orifices at an end of the adjoined substrates, a step of coating the face constituting the external surface of the aforementioned member with a material with superhydrophilicity, and a step of causing the orifices to communicate with the respective liquid flow paths.
According to the present invention, there is provided a method for producing a liquid discharge head comprising a step of forming a heat generating element for generating thermal energy on an element substrate consisting of silicon, a step of forming a liquid flow path corresponding to the heat generating element, a step of forming a supply aperture for supplying the liquid flow path with liquid, a step of forming a member for forming an orifice for discharging the liquid, a step of coating the member with a superhydrophilic material, and a step of forming an orifice in the coated member.
The material with superhydrophilicity means such a material that liquid deposited thereon does not form a liquid drop but forms a substantially zero contact angle with such material. The contact angle is measured for example by a contact angle meter CA-X150 manufactured by Kyowa Kaimen Kagaku Co., Ltd. and can be defined preferably not exceeding 5xc2x0 and more preferably not exceeding 4xc2x0. The characteristics of the face can be further improved if the contact angle is within the above-mentioned range.
In the present invention, as the face is coated with the material with superhydrophilicity, the smear induced by the liquid deposited on such face does not form a liquid drop but is spread as a thin film over the entire face, whereby formation of a particle by drying can be prevented. Consequently, there can be prevented clogging of the orifice or the discharge port by the particle induced by smear, and the liquid discharge head of the present invention can maintain satisfactory performance over a prolonged period.
Examples of the member for removing the smear deposited on the face without contact therewith include an air nozzle or a water nozzle provided in the vicinity of the discharge port for the liquid. Such member blows off the smear floating on the face, thereby effectively removing the smear without contacting the face.